Of course! I never thought that water vapour can also escape up through the floor of the oven - kept wondering where it would go once the oven was weatherproofed...
Roeland, I'm pretty sure dmun has insulation under his oven, and the concrete slab underneath that still gets warm (right dmun?) I also think that you're right about the miosture making the corrugated steel hot. Every time I put a new layer of anything with moisture in it on the top of my oven the next firing makes it warm to the touch... and then after a couple of firings (and lots of worrying) it stops again.